Where internal organisation is concerned, since the late 1990s REN has been implementing and developing quality, environment, health and safety management systems.

At Rede Eléctrica Nacional, the first milestone in the official recognition of these systems was NP EN ISO 9001 certification of the quality management system in the planning and construction of extra-high voltage lines and substations in April 2000.

This was followed by NP EN ISO 14001 certification of REN’s environmental management system, covering the whole concession, in December 2003.

Finally, in December 2005 the three branches of the integrated quality, environment and safety management system were certified and have recently been submitted for renewal alongside with the transition of the safety management system to the new edition of the corresponding standard.

At the end of 2008, APCER renewed the triple certification of the integrated management systems of Rede Eléctrica Nacional and certified, for the first time, the integrated quality, environment and safety management systems  of two other companies: REN Serviços and REN Trading.

REN Group’s gas companies also have these management systems, in spite of the loss of certification resulting from their split from GALP and inclusion in REN in September 2006. Work was done in 2007 on adapting the main processes and procedures that resulted in the certification of both REN Gasodutos and REN Atlântico's integrated management systems in July 2009.

Keeping in mind the development of quality, environment, health and safety management systems and the expansion of its certification to most of the companies, a Quality, Environment and Safety Committee was set up in early 2008 at each of the following companies: Rede Eléctrica Nacional, REN Gasodutos + REN Armazenagem, REN Atlântico and REN Serviços.